The present invention relates to a tire changing machine for industrial vehicle wheels.
As it is known, despite considerable progress in recent decades in terms of automation of tire fitting, bead release and tire removing operations, fitting and removal of industrial vehicle tires still require considerable manual effort and great skill by the operator, who must intervene several times in a tire fitting or removal operation with the risk of injuring himself.
The main object of the present invention is to provide a new tire changing machine suitable for performing in a substantially automatic manner various operations including gripping a wheel rim-tire assembly or just the wheel rim, fixing it in position and fitting bead release and removing of the tire.
Another object of the present invention is to provide a tire changing machine which is of universal use for wheels of flanged-rim, inverted-channel or bead-wire type.
Another object of the present invention is to provide a new bead release or breaking away and removal method which is highly effective and fast to be carried out.
According to a first aspect of the present invention, there is provided a tire changing machine which has a support frame, rotatable supporting means for a wheel rim, locking means for securing said wheel rim to said supporting means, a fitting tool securable to an adjustable tool supporting arm carried by said support frame, and driving means for said rotatable supporting means, and is characterized in that it comprises at least one first and second pressure rollers which can be located in diametrically opposite positions with respect to a wheel rim carried by said supporting means and are arranged to act on either side of the wheel rim, and control means designed to act, upon control, on each said first and second rollers.
Advantageously, said supporting means comprises a flange-type mandrel assembly for supporting a wheel rim, said mandrel assembly is telescopic and arranged with its axis of rotation at a relatively small angle with respect to the horizontal, and can be raised and lowered in order to adapt to various wheel rim dimensions.
According to another aspect of the present invention, there is provided a method of releasing or breaking away the bead of a tire rigidly coupled to a rotating support and of removing said tire, said method being characterized in that it comprises:
applying to a tire at least one pair of bead releasing rollers which are arranged diametrically opposite to one another while acting on opposite sides on said tire;
rotating the tire while said bead releasing rollers apply mutually opposite but staggered pressures in order to break-away the bead of the tire on both sidewalls; and
stopping the pressure action of one of the bead breaker rollers while the other one is still pressing against the tire until removal from the wheel rim is completed.